Aquahawk, offered to me through BMMD, tripped thresholds that indicated I had a water leak at the Nest. It'd clearly been happening for a while (see graph) but had not tripped indicators till late Feb when we were "using" 11gal/hr when not even in Summit. Yikes. I ripped up to Summit and checked all the possible culprits like faucents, toilets, outside nibs, new washer hook ups, etc. but no sounds were tipping me off.
Even in the water heater closet there was no unusual noise at this leak
rate... but I checked the various hoses into the drain and discovered
the one attached to the pressure-temperature relief valve was squirting. I tested the valve with the lever there and it continued leaking ~ I found the cause. I got the specs for the part: a Watts L 40XL 200psi/150°F; kind of a heavy duty one as our water heater also runs the radiant heating. But no plumbing supply place was even open in Summit CO on the weekend. I ordered the right part for $240 from AMZ but they would not deliver to my house or PO Box in Silverthorne so I had it sent to COS and I returned to the Front Range to get it. I couldn't turn off the water as, as mentioned, it heats the house too and at 10K ft elevation we need the heat on to stop stuff from freezing even when not there.
Then, an epic storm hit the southwest and the part did not arrive as hoped in the 5 days promised. So, I canvassed COS plumbing supply spots and found Rampart had the part in stock. I rushed out to buy it for $130 all up and headed back to Silverthorne. The other part will serve as backup, whenever it arrives.
To remove the old valve I had to take down the hard copper drain piping first as I couldn't rotate the valve before removing the rigid structure. Not a great plumbing design IMO. I turned off the main water supply and drained the top of the tank to below the relief valve. I initially tried to heat an appropriate spot on the structure so I could disassemble it and then reassemble, but it was old and didn't loosen. I ultimately had to cut the down drain pipe.
Once removed I observed the corrosion and sediment in the old relief valve which fouled it. It was likely caused by the harder water in Summit Co. I reused the down drain copper but redesigned the bottom of it with a removable horizontal run so when it happens again I won't have to do too much work to replace the valve; heck, I even have a 2X priced, late-delivered backup now. I sanded the pipe, wire brushed it, added flux to it, and sweat the 3/4" to 3/4" threaded female adapter to it using a torch and solder as normal.
I reinstalled the down pipe and used a plastic screw-in elbow from threaded to nib and attached a reinforced plastic pipe to run to the drain. All done. The Nest isn't leaking now. However, the months of slow leaking very hot water and the delays in receiving the replacement part allowing repair made our water and power/gas bill go up by at least a $1K for the period. Sheesh.
